<?php
/**
 * XML-parsing classes to wrap the domxml and DOM extensions for PHP 4
 * and 5, respectively.
 *
 * @package OpenID
 */

/**
 * The base class for wrappers for available PHP XML-parsing
 * extensions.  To work with this Yadis library, subclasses of this
 * class MUST implement the API as defined in the remarks for this
 * class.  Subclasses of Auth_Yadis_XMLParser are used to wrap
 * particular PHP XML extensions such as 'domxml'.  These are used
 * internally by the library depending on the availability of
 * supported PHP XML extensions.
 *
 * @package OpenID
 */
class Auth_Yadis_XMLParser {

  /**
   * Initialize an instance of Auth_Yadis_XMLParser with some
   * XML and namespaces.  This SHOULD NOT be overridden by
   * subclasses.
   *
   * @param string $xml_string A string of XML to be parsed.
   * @param array $namespace_map An array of ($ns_name => $ns_uri)
   * to be registered with the XML parser.  May be empty.
   * @return boolean $result True if the initialization and
   * namespace registration(s) succeeded; false otherwise.
   */
  function init($xml_string, $namespace_map) {
    if (! $this->setXML($xml_string)) {
      return false;
    }
    
    foreach ($namespace_map as $prefix => $uri) {
      if (! $this->registerNamespace($prefix, $uri)) {
        return false;
      }
    }
    
    return true;
  }

  /**
   * Register a namespace with the XML parser.  This should be
   * overridden by subclasses.
   *
   * @param string $prefix The namespace prefix to appear in XML tag
   * names.
   *
   * @param string $uri The namespace URI to be used to identify the
   * namespace in the XML.
   *
   * @return boolean $result True if the registration succeeded;
   * false otherwise.
   */
  function registerNamespace($prefix, $uri) {  // Not implemented.
  }

  /**
   * Set this parser object's XML payload.  This should be
   * overridden by subclasses.
   *
   * @param string $xml_string The XML string to pass to this
   * object's XML parser.
   *
   * @return boolean $result True if the initialization succeeded;
   * false otherwise.
   */
  function setXML($xml_string) {  // Not implemented.
  }

  /**
   * Evaluate an XPath expression and return the resulting node
   * list.  This should be overridden by subclasses.
   *
   * @param string $xpath The XPath expression to be evaluated.
   *
   * @param mixed $node A node object resulting from a previous
   * evalXPath call.  This node, if specified, provides the context
   * for the evaluation of this xpath expression.
   *
   * @return array $node_list An array of matching opaque node
   * objects to be used with other methods of this parser class.
   */
  function evalXPath($xpath, $node = null) {  // Not implemented.
  }

  /**
   * Return the textual content of a specified node.
   *
   * @param mixed $node A node object from a previous call to
   * $this->evalXPath().
   *
   * @return string $content The content of this node.
   */
  function content($node) {  // Not implemented.
  }

  /**
   * Return the attributes of a specified node.
   *
   * @param mixed $node A node object from a previous call to
   * $this->evalXPath().
   *
   * @return array $attrs An array mapping attribute names to
   * values.
   */
  function attributes($node) {  // Not implemented.
  }
}

/**
 * This concrete implementation of Auth_Yadis_XMLParser implements
 * the appropriate API for the 'domxml' extension which is typically
 * packaged with PHP 4.  This class will be used whenever the 'domxml'
 * extension is detected.  See the Auth_Yadis_XMLParser class for
 * details on this class's methods.
 *
 * @package OpenID
 */
class Auth_Yadis_domxml extends Auth_Yadis_XMLParser {

  function Auth_Yadis_domxml() {
    $this->xml = null;
    $this->doc = null;
    $this->xpath = null;
    $this->errors = array();
  }

  function setXML($xml_string) {
    $this->xml = $xml_string;
    $this->doc = @domxml_open_mem($xml_string, DOMXML_LOAD_PARSING, $this->errors);
    
    if (! $this->doc) {
      return false;
    }
    
    $this->xpath = $this->doc->xpath_new_context();
    
    return true;
  }

  function registerNamespace($prefix, $uri) {
    return xpath_register_ns($this->xpath, $prefix, $uri);
  }

  function &evalXPath($xpath, $node = null) {
    if ($node) {
      $result = @$this->xpath->xpath_eval($xpath, $node);
    } else {
      $result = @$this->xpath->xpath_eval($xpath);
    }
    
    if (! $result) {
      $n = array();
      return $n;
    }
    
    if (! $result->nodeset) {
      $n = array();
      return $n;
    }
    
    return $result->nodeset;
  }

  function content($node) {
    if ($node) {
      return $node->get_content();
    }
  }

  function attributes($node) {
    if ($node) {
      $arr = $node->attributes();
      $result = array();
      
      if ($arr) {
        foreach ($arr as $attrnode) {
          $result[$attrnode->name] = $attrnode->value;
        }
      }
      
      return $result;
    }
  }
}

/**
 * This concrete implementation of Auth_Yadis_XMLParser implements
 * the appropriate API for the 'dom' extension which is typically
 * packaged with PHP 5.  This class will be used whenever the 'dom'
 * extension is detected.  See the Auth_Yadis_XMLParser class for
 * details on this class's methods.
 *
 * @package OpenID
 */
class Auth_Yadis_dom extends Auth_Yadis_XMLParser {

  function Auth_Yadis_dom() {
    $this->xml = null;
    $this->doc = null;
    $this->xpath = null;
    $this->errors = array();
  }

  function setXML($xml_string) {
    $this->xml = $xml_string;
    $this->doc = new DOMDocument();
    
    if (! $this->doc) {
      return false;
    }
    
    if (! @$this->doc->loadXML($xml_string)) {
      return false;
    }
    
    $this->xpath = new DOMXPath($this->doc);
    
    if ($this->xpath) {
      return true;
    } else {
      return false;
    }
  }

  function registerNamespace($prefix, $uri) {
    return $this->xpath->registerNamespace($prefix, $uri);
  }

  function &evalXPath($xpath, $node = null) {
    if ($node) {
      $result = @$this->xpath->query($xpath, $node);
    } else {
      $result = @$this->xpath->query($xpath);
    }
    
    $n = array();
    
    if (! $result) {
      return $n;
    }
    
    for ($i = 0; $i < $result->length; $i ++) {
      $n[] = $result->item($i);
    }
    
    return $n;
  }

  function content($node) {
    if ($node) {
      return $node->textContent;
    }
  }

  function attributes($node) {
    if ($node) {
      $arr = $node->attributes;
      $result = array();
      
      if ($arr) {
        for ($i = 0; $i < $arr->length; $i ++) {
          $node = $arr->item($i);
          $result[$node->nodeName] = $node->nodeValue;
        }
      }
      
      return $result;
    }
  }
}

global $__Auth_Yadis_defaultParser;
$__Auth_Yadis_defaultParser = null;

/**
 * Set a default parser to override the extension-driven selection of
 * available parser classes.  This is helpful in a test environment or
 * one in which multiple parsers can be used but one is more
 * desirable.
 *
 * @param Auth_Yadis_XMLParser $parser An instance of a
 * Auth_Yadis_XMLParser subclass.
 */
function Auth_Yadis_setDefaultParser(&$parser) {
  global $__Auth_Yadis_defaultParser;
  $__Auth_Yadis_defaultParser = & $parser;
}

function Auth_Yadis_getSupportedExtensions() {
  return array(
      'dom' => array('classname' => 'Auth_Yadis_dom', 'libname' => array('dom.so', 'dom.dll')), 
      'domxml' => array('classname' => 'Auth_Yadis_domxml', 
          'libname' => array('domxml.so', 'php_domxml.dll')));
}

/**
 * Returns an instance of a Auth_Yadis_XMLParser subclass based on
 * the availability of PHP extensions for XML parsing.  If
 * Auth_Yadis_setDefaultParser has been called, the parser used in
 * that call will be returned instead.
 */
function &Auth_Yadis_getXMLParser() {
  global $__Auth_Yadis_defaultParser;
  
  if (isset($__Auth_Yadis_defaultParser)) {
    return $__Auth_Yadis_defaultParser;
  }
  
  $p = null;
  $classname = null;
  
  $extensions = Auth_Yadis_getSupportedExtensions();
  
  // Return a wrapper for the resident implementation, if any.
  foreach ($extensions as $name => $params) {
    if (! extension_loaded($name)) {
      foreach ($params['libname'] as $libname) {
        if (@dl($libname)) {
          $classname = $params['classname'];
        }
      }
    } else {
      $classname = $params['classname'];
    }
    if (isset($classname)) {
      $p = new $classname();
      return $p;
    }
  }
  
  if (! isset($p)) {
    trigger_error('No XML parser was found', E_USER_ERROR);
  } else {
    Auth_Yadis_setDefaultParser($p);
  }
  
  return $p;
}
